Step 1: Prepare your pie crust. On a lightly floured surface, roll out your pie crust to a 12-inch circle. Carefully transfer it to a 9-inch pie plate. Trim the edges, leaving about a 1/2-inch overhang, then fold it under and crimp decoratively. Prick the bottom of the crust all over with a fork.
Step 2: Blind bake the crust. Line the pie crust with parchment paper and fill with pie weights or dried beans. Bake in a preheated oven at 375°F (190°C) for 15 minutes. Remove the weights and parchment, then bake for another 5-7 minutes, or until the crust is lightly golden. Let it cool slightly.
Step 3: Cook the bacon. While the crust is baking, cook the diced bacon in a skillet over medium heat until crispy. Using a slotted spoon, transfer the cooked bacon to a plate lined with paper towels to drain excess fat.
Step 4: Assemble the fillings. Sprinkle the drained crispy bacon evenly over the bottom of the cooled, blind-baked pie crust. Then, distribute the grated Gruyère cheese over the bacon.
Step 5: Prepare the custard. In a large bowl, whisk together the eggs, heavy cream, salt, black pepper, and a pinch of nutmeg until just combined. Be careful not to over-whisk, as too much air can cause bubbles in the custard.
Step 6: Pour and bake. Carefully pour the egg mixture over the bacon and cheese in the pie crust. Transfer the pie plate to a baking sheet (this makes it easier to handle). Bake at 375°F (190°C) for 35-45 minutes, or until the center is just set and the top is golden brown. A knife inserted near the center should come out clean.
Step 7: Cool and serve. Remove the quiche from the oven and let it cool on a wire rack for at least 10-15 minutes before slicing and serving. This allows the custard to set completely, ensuring clean slices.